A compound being studied for a medical condition is not the same as an approved treatment. SARMs research includes different candidates, patient groups and development stages. The useful question is what each study establishes.
What do clinical trials investigate?
Early trials commonly examine tolerability and how a compound behaves in the body. Later trials investigate efficacy and safety in defined populations. Study designs vary, and reaching a later phase does not guarantee a positive result or regulatory approval.
The FDA's explanation of clinical research sets out these distinctions in the US development process. It is not a UK marketing permission for a retail product.
From candidate to licensed medicine
In short: in the UK a medicine needs a marketing authorisation from the MHRA, and no SARM has one.
A phase I study usually enrols a small number of volunteers and measures safety and pharmacokinetics. Phase II studies test the compound against a placebo in the patient group of interest and look for a signal on the outcome that matters. Phase III trials are larger and longer and are designed to show a clinically meaningful benefit with an acceptable safety profile. Only then can a company apply to a regulator such as the Medicines and Healthcare products Regulatory Agency for a marketing authorisation.
Most candidates in any therapeutic area stop before that point. SARMs are no exception: after more than 25 years of research, none has completed the path.
Examples of different research questions
In short: the best known human SARM studies each asked a different question in a different population.
| Candidate | Example publication | Question examined |
|---|---|---|
| Enobosarm / Ostarine | 2011 phase II study | Body composition, function and safety in older adults |
| LGD-4033 | 2012 study in healthy men | Safety, biological measurements and body composition under a defined protocol |
| RAD-140 | First-in-human oncology study | Early clinical assessment in a defined breast-cancer population |
These examples are not a live pipeline ranking or a comparison of which compound is best. Their study questions and participants differ.
What happened to the leading programmes
In short: each of the main programmes stalled for a different reason, and none reached a licence.
Enobosarm (Ostarine). After the 2011 phase II study in older adults, a randomised phase II trial in patients with cancer related muscle wasting was published by Dobs and colleagues in 2013. The phase III POWER trials that followed, whose design is described by Crawford and colleagues (2016), were run in lung cancer patients and did not lead to approval. The compound has since been studied in breast cancer, including a randomised phase II trial reported by Palmieri and colleagues in 2024.
LGD-4033 (VK5211). The phase I study in healthy men was followed by a phase II trial in older patients recovering from hip fracture, which the developer reported at a conference in 2018 rather than in a full journal paper. No phase III trial has been published.
RAD-140. Human exposure is limited to a small first-in-human study in women with advanced breast cancer, reported by LoRusso and colleagues in 2022.
Andarine (S-4). Andarine had a substantial animal research record but did not progress far in human trials; its development was overtaken by enobosarm.
Why do endpoints matter?
In short: an endpoint is the result a study is designed to measure, and a positive result on one endpoint does not prove another.
An endpoint is the result a study is designed to measure. Lean mass, physical function and a cancer outcome are different endpoints. A positive finding on one cannot automatically establish another.
Also ask whether the result came from a controlled comparison, whether the main endpoint was met, what adverse events were recorded and how much uncertainty remains. A headline about a promising result is not the whole assessment.
This is the main reason the SARM programmes stalled. The trials repeatedly showed changes in lean body mass, but regulators look for improvements in how patients function and feel, and those were harder to demonstrate.
Does selectivity mean no side effects?
In short: no. The trials recorded hormone and cholesterol changes, and case reports describe liver injury.
A research objective to separate desired from unwanted activity does not establish that a compound is harmless. In the published trials, SARMs lowered testosterone and HDL cholesterol in a dose related way, and a growing case literature describes liver injury in people using products sold as SARMs (for example Flores and colleagues, Hepatology Communications, 2020). The FDA warns about serious risks associated with SARMs. Our SARMs safety guide explains why trial context and product identity matter when interpreting safety claims.
What does this mean for research-product listings?
In short: a clinical paper describes the material and conditions in that study, not any product on sale.
A clinical publication concerns the material and conditions studied. It does not certify another supplier's bottle or authorise its use as a treatment. Claims about a retail product must not be inferred from a candidate's medical development programme. Product surveys such as Van Wagoner and colleagues (JAMA, 2017) found that many products sold online as SARMs did not contain what their labels stated, which is a further reason not to read trial results across to retail material.
For the origins of the field, see the SARMs research timeline. This article explains clinical evidence; it does not recommend a treatment or predict which candidate will become a medicine.
Frequently asked questions
Are SARMs used in medicine today? No. No SARM is a licensed medicine in the UK or anywhere else, so none can be prescribed.
Which SARM got closest to approval? Enobosarm (Ostarine), which reached phase III trials in cancer related muscle wasting.
What conditions have SARMs been studied for? Mainly muscle wasting linked to cancer and ageing, recovery after hip fracture, bone loss in animal models and some forms of breast cancer.
Could a SARM still become a medicine? Research continues in some areas, particularly breast cancer, but no current programme guarantees approval and this guide makes no prediction.
Sources
- Dalton JT et al. (2011). The selective androgen receptor modulator GTx-024 (enobosarm) improves lean body mass and physical function in healthy elderly men and postmenopausal women. J Cachexia Sarcopenia Muscle. PubMed 22031847
- Basaria S et al. (2013). The safety, pharmacokinetics, and effects of LGD-4033 in healthy young men. J Gerontol A Biol Sci Med Sci. PubMed 22459616
- Dobs AS et al. (2013). Effects of enobosarm on muscle wasting and physical function in patients with cancer. Lancet Oncol. PubMed 23499390
- Crawford J et al. (2016). Study design and rationale for the phase 3 clinical development program of enobosarm (POWER trials). Curr Oncol Rep. PubMed 27138015
- LoRusso P et al. (2022). A first-in-human phase 1 study of RAD140 in ER+/HER2- metastatic breast cancer. Clin Breast Cancer. PubMed 34565686
- Palmieri C et al. (2024). Activity and safety of enobosarm in advanced breast cancer (Study G200802). Lancet Oncol. PubMed 38342115
- Flores JE et al. (2020). Drug-induced liver injury by selective androgenic receptor modulators. Hepatol Commun. PubMed 32140660
- Van Wagoner RM et al. (2017). Chemical composition and labeling of substances marketed as selective androgen receptor modulators and sold via the internet. JAMA. PubMed 29183075
- Narayanan R, Coss CC, Dalton JT (2018). Development of selective androgen receptor modulators (SARMs). Mol Cell Endocrinol. PubMed 28624515